saltwater tank/reef tank

Question
my question is I have an fish only saltwater tank ,and I am looking to turn it in to a reef tank. The only problem i have is that the way the tank was setup I can. It has an under gravel kit with crush coral no sand. So my question is what would happen if I removed the coral and under gravel kit and put it live sand and live rock

Answer
Well, my recommendation is to house your fish separately in another fish only aquarium for one month when you do this changeover.

The reason is, when you lift the undergravel filtration unit, diseased bacteria is going to rush into the tank water and ruin it.  It may take many cycles to get rid of it.  Therefore, I suggest instead, draining the tank, emptying it, washing it and starting fresh.

I hope this is helpful.  Please write back if you have any further questions.

Happy fish-keeping!

:)